To improve fuel economy, conventionally known are vehicles capable of executing a lock-up control for slip engaging a lock-up clutch at the time of deceleration and an economic run control for executing inertia traveling by interrupting a power transmission from an engine to driving wheels by disengaging a clutch. In the vehicles, when a vehicle speed is decreased by an abrupt brake operation during the lock-up control and the economic run control, there is a fear that an engine stall occurs and the engine stops.
It is preferable to accurately detect a generation of an abrupt deceleration state so that the controls can be interrupted at once at the time of abrupt deceleration. For examples, Patent Literatures 1, 2 disclose technologies for the improving a determination accuracy of an abrupt deceleration state by using together plural abrupt deceleration determining means, for example, an abrupt deceleration determining means based on a brake operation, and an abrupt deceleration determining means based on a change rate (a degree of deceleration) of each wheel speed.
Further, Patent Literature 3 discloses a technology for changing a threshold value of an abrupt deceleration determination according to whether or not a brake operation and an acceleration operation are executed.